1) At 01:08 p.m. on Nov. 28, there was an explosion-like sound on the second floor of a factory in Gamjeon-dong, Sasang District, Busan. This was accompanied by a leak of poisonous gas assumed to be hydrogen sulfide, according to the Busan Fire Department.

2) Out of the seven waste water management workers who were working at the time, four are known to have fainted after inhaling the gas.

3) “The poisonous gas, assumed to be hydrogen sulfide, was leaked while workers were working. Firefighters have rescued four workers who fell unconscious after inhaling the gas. Two people were in good condition, so a total of six workers were transferred to a hospital. One person is in good health, so he is resting here.” - Ryu Seung-hun, 119 director of the Busan Fire Department

4) “At 14:21, 150 parts per million of poisonous gas was measured to have been leaked. There was no indication of [gas] leaking to the outside.” - Ryu